The Bronchi and Lungs Overview

The Bronchi and Subdivisions: The Bronchial Tree

• The respiratory zones initiate at terminal bronchioles leading to respiratory bronchioles, followed by alveolar ducts, sacs, and alveoli.
• Alveoli are the functional units of lungs where gas exchange between blood and air occurs.

Summary of the Pathway of Air

• Airflow sequence: External nose → Internal Nose (Nasal cavity) → Pharynx → Larynx → Trachea → Main (primary) bronchi → Lobar (secondary) bronchi → Segmental (tertiary) bronchi → Bronchioles → Terminal bronchioles → Respiratory bronchioles → Alveolar ducts → Alveolar sacs → Alveoli.
• Branching of primary bronchi occurs inside the lungs.

The Lungs

• Lungs are principal organs of respiration, connected to the heart and trachea at the hilum.
• Characteristics: Soft, spongy, elastic, weighing 0.5 kg each (1 kg total); cone-shaped, apex about 1 inch above the clavicle; pink in infants, dark gray in adults; inflated lungs float while fetal lungs sink in water.

Pulmonary Ventilation: Inspiration and Expiration

• Involves two phases: inspiration (inhaling) and expiration (exhaling).

Gas Exchange

• External respiration occurs in the alveoli where oxygen and carbon dioxide exchange between lungs and blood.
• Internal respiration involves gas exchange between blood and tissues.
• Oxygen Transport: 98.5% binds to hemoglobin as oxyhemoglobin, 1.5% remains dissolved in plasma.
• Carbon Dioxide Transport: 7% dissolved in plasma, 23% attached to hemoglobin (carbaminohemoglobin), 70% as bicarbonate ions.

Control of Respiration

• Medullary respiratory centers include the dorsal inspiratory group, which regulates the rhythm of breathing.
• Inspiratory neurons activate diaphragm and external intercostals; expiration occurs passively when these muscles relax.
• Normal respiratory rate ranges from 12 to 20 breaths per minute.

Nursing Diagnoses: Impaired Gas Exchange

• Definition: Imbalance in oxygenation and carbon dioxide elimination at the alveolar-capillary membrane.
• Related Factors: Ventilation-perfusion mismatch, alveolar-capillary membrane changes (e.g., ARDS, pneumonia), and hypoventilation (e.g., COPD).

Defining Characteristics

• Abnormal arterial blood gases (e.g., low PaO₂, high PaCO₂).
• Symptoms include cyanosis, confusion, dyspnea, fatigue, and tachypnea.

Goals/Outcomes for Patients

• Maintain optimal gas exchange indicated by normal ABG values.
• Patient should show relief from dyspnea and signs of adequate oxygenation.

Nursing Interventions

• Monitor ABGs and SpO₂ to evaluate gas exchange.
• Administer supplemental oxygen as needed to correct hypoxemia.
• Position patients to enhance lung expansion (e.g., Fowler’s position).
• Encourage controlled breathing techniques, such as pursed-lip breathing.
• Collaborate with respiratory therapists for potential mechanical ventilation needs.